package acwing.二分;

import java.io.BufferedReader;
import java.io.InputStreamReader;

/**
 * @description:
 * @author: qian
 * @createDate: 2021/11/10
 */
public class 数的三次方根 {

    static double n;
    static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws Exception{
        n = Double.parseDouble(in.readLine());
        double l = -1000, r = 1000;
        while (r - l > 1e-8) {
            double mid = (l + r) / 2;
            if (mid * mid * mid >= n) r = mid;
            else l = mid;
        }
        System.out.printf("%.6f", r);
        in.close();
    }
}
